The name of the file where this frame was loaded from.
This is a read-only property that describes the origin of the frame. When a frame is loaded from a Jay or CSV file, this property will contain the name of that file. Similarly, if the frame was opened from a URL or a from a shell command, the source will report the original URL / the command.
Certain sources may be converted into a Frame only partially,
in such case the
source property will attempt to reflect this
fact. For example, when opening a multi-file zip archive, the
source will contain the name of the file within the archive.
Similarly, when opening an XLS file with several worksheets, the
source property will contain the name of the XLS file, the name of
the worksheet, and possibly even the range of cells that were read.
If the frame was loaded from a file or similar resource, the
name of that file is returned. If the frame was computed, or its
data modified, the property will return